1. Field of the Invention
The present invention relates to a lens barrel having a manual focus function, a method of controlling the lens barrel, a camera body, a method of controlling the camera body, an imaging device, and a method of controlling the imaging device.
2. Description of the Related Art
A single lens reflex camera for an expert or the like has a manual focus function that allows a user to manually adjust a focus. A camera having this manual focus function includes an operation ring that is operated by a user and a drive unit that moves a focus lens according to the rotation angle or the angular position of the operation ring.
An operation ring is mounted on each of cameras disclosed in JP5028945B (corresponding to U.S. Pat. No. 7,969,672) and JP2013-7837A (corresponding to U.S. Pat. Nos. 9,013,607 and 9,235,026) so as to be movable between a first position and a second position in the direction of an optical axis of an imaging optical system including a focus lens. The operation ring is endlessly rotatable in a case in which the operation ring is present at the first position, and is rotatable about the optical axis within a limited angular range in a case in which the operation ring is present at the second position. Further, imaging is performed in a first manual focus mode in a case in which the operation ring is present at the first position. In the first manual focus mode, the focus lens is moved according to the rotation angle of the operation ring. On the other hand, imaging is performed in a second manual focus mode in a case in which the operation ring is present at the second position. In the second manual focus mode, the focus lens is moved according to the angular position of the operation ring. In the camera disclosed in JP2013-7837A, a distance scale is provided on the operation ring and an index is provided on a lens barrel body. In the second manual focus mode, the camera disclosed in JP2013-7837A moves the focus lens to a position at which an imaging distance corresponding to the distance scale set to the position of the index is obtained.
In the cameras disclosed in JP50289453 and JP2013-7837A, the operation ring is adapted to be rotatable and to be movable in the direction of the optical axis. For this reason, there is a possibility that an erroneous operation is caused at the time of switching of the first and second manual focus modes. For example, in a case in which a mode is changed to the first manual focus mode in order to finely adjust an imaging distance from the set value of the imaging distance after the imaging distance is set in the second manual focus mode, the imaging distance can be finely adjusted from this set value assuming that the operation ring can be moved to the first position from the second position in the direction of the optical axis without being rotated. However, the operation ring may be rotated by mistake in a case in which the operation ring is to be moved in the direction of the optical axis.
In regard to this erroneous operation, JP2013-7837A discloses a structure that electrically forbids processing corresponding to the rotation of the operation ring even though the operation ring rotates in the event that the operation ring is moved in the direction of the optical axis. Specifically, until a predetermined period has passed after the switching of the operation ring is detected, the movement of the focus lens corresponding to the rotation of the operation ring is inhibited even though the operation ring rotates.
However, a circuit for electrically preventing an erroneous operation needs to be separately provided in a countermeasure against the erroneous operation disclosed in JP2013-7837A. Further, since there is a variation in the time in which users switch the operation ring, the predetermined period needs to be set to be long to some extent in order to reliably prevent the erroneous operation. However, in a case in which the predetermined period is set to be long, time, which has passed until the rotation of the operation ring becomes effective after an operation for switching the operation ring, is lengthened. For this reason, users feel uncomfortable. On the contrary, in the event that the predetermined period is set to be short so that users do not feel uncomfortable, it is not possible to reliably prevent an erroneous operation.